A "USB to female" cable, also called a "USB female to female" cable, is essentially an extension cable that allows you to connect a standard male USB connector to another device by providing a female USB port at the end, effectively extending the reach of your existing USB cable or acting as a coupler to join two male USB cables together; it's primarily used to increase the distance between a device and a computer's USB port or to connect multiple devices to a single USB port using adapters.